"This is a record for us. We've never had such an incident with so many victims," Doering told reporters. "It's not a scene that I would want anybody to see."
A family member called 911 at about 8 a.m. Saturday after discovering the bodies inside a dingy mobile home shaded by large, moss-draped oaks with an old boat in the front yard.
At an afternoon news conference, Doering declined to say whether police believe the killer was among the dead or remained at large. No arrests had been made.
Investigators were interviewing neighbors about whether they saw or heard anything unusual Saturday morning.
The two injured victims were taken to a Savannah hospital 60 miles away and were in critical condition, Doering said.
By early Saturday evening, four of the seven bodies had been removed from the crime scene. Some of the victims had been tentatively identified, but Doering would not release any names or ages.
"I really don't know the ages," Doering said. "There were some older-aged victims and we believe there were some in their teens."
Located a few miles north of the port city of Brunswick, the mobile home park consists of about 100 spaces and is nestled among centuries-old live oak trees near the center of New Hope Plantation, according to the plantation's Web site.
The 1,100 acre tract is all that remains of a Crown grant made in 1763 to Henry Laurens, who later succeeded John Hancock as president of the Continental Congress in 1777.
Laurens obtained control of the South Altamaha river lands and named it New Hope Plantation, according to the plantation's Web site.
Lisa Vizcaino, who has lived at New Hope for three years, said the management works hard to keep troublemakers out of the mobile home park and that it tends to be quiet.
"New Hope isn't rundown or trashy at all," Vizcaino said. "It's the kind of place where you can actually leave your keys in the car and not worry about anything."
Vizcaino said she didn't know the victims and heard nothing unusual when she woke up at 7 a.m. Saturday morning. After word of the slayings spread, she said, the park was quieter than usual. "Everybody had pretty much stayed in their houses," Vizcaino said. "Normally you would see kids outside, but everybody's been pretty much on lockdown."